Recovering gasoline



March 17, 1931. F E; HQSMER v 1,796,755

RECOVERING GASOLINE Filed June 16, 1926 l l n THW/f Patented- Mar. 17,` 1931 PATENT OFFICE mann n Hosmnraior non'r wonen, TEXAS REGOVEBING GASOLINE applicativa mea :rune is,

This invention relates to recovering gasoline; and it comprises a method of directly recovering a marketable gasoline from natural gas, casinghead gas and the like wherein such gas is refrigerated under line pressures by the evaporation of light oils thereinto, l thereby condensing the heavy oils (gasoline), the heavy oils are collected and removed and refrigerated as is passed into heat exchanging relations i to the incoming gas and is then placed un er sufficient pressure and temperature to condense light oils therefrom, the condensate of light oils so obtained being returned to serve in refrigerating the incoming gas; and it further comprises a new organization of apparatus elements useful in such method; all as more fully hereinafter set forth and as claimed.

In the recovery of gasoline from natural gas and casinghead gas, a wide variety of processes have been proposed and are in use, utilizing pressure, chilling and scrubbin in various ways. All these processes pro uce V what is known as a wild gasoline, that is, a gasoline containing very volatile components which must beweathered out in making commercial gasoline. In weathering, however, there is a vloss of desirable, less volatile products which accompany vapors of the very l volatile components. It is the object of the present invention to produce in a simple direct wa a gasoline requiring little .or no weathering; and to accomplish this with a minimum plant' equipment.

Wet natural as contains in addition to methane and et ane, which are permanent gases for the present purposes, a wide variety of vapors of condensable hydrocarbons; these rangmg frompropane up through the 40 butanes, the pentanes, the hexanes, etc. On

condensation, these vapors give liquids of decreasing volatility in the order given. In the-terminology of the art, these volatile liquids are called oils, and this nomenclature will be adopted here, the very volatile oils be- 1926. Serial No. 116,432.

ing termed light oils and the less volatile oils, the heavy oils; it being understood, however, that these heavy oils produced in the present process are of the nature of gasoline.

In the present invention, natural gas coming from any suitable source is usually, but not always, put under some degree of pres sure'by a pump if the line pressure bedeemed not sulicient. In this stage of operation, the gas may, indeed, be at ordinary or atmospheric pressure, although I find it better to work under at least a few pounds extra pressure. After compression, the gas is cooled in an ordinary way. Any condensate which may be produced at ,this point is removed, w from the system. The as is now further cooled in a pre-cooler y passing through .pipes in counter current, heat exchanging relation to an exteriorly conducted cooling gas resulting from a later step in the operation. The precooled gas is then refrigerated by the evaporation into it of a liquid body of light oils sprayed into the gas. This condensate of light oils is produced in a subsequent step of the process. The self-evaporation of the light oil condensate produces a very low temperature and the heavy oil vapors in the gas are condensed, thereby directly producing a marketable gasoline. The gasoline produced is substantially free from those light oils which produce wildness. The condensed liquid (gasoline) and the remaining gas are now separated. The liquid is sent out of the 'system to storage tanks. The cold gas containing the produced vapors is first used to pre-cool as going to the evaporation or spray cham er and then goes to a final compressor Where it is put under pressure and cooled by water cooling or in any other convenient way. This results in the production of a'body of condensate containing mainly the li ht oils. I adjust the pressure and cooling in t is final operation to such a point that some, but not all, of the very light oils are condensed. By

so doing, there 4is gradually built up a body incoming gas. As will be perceived, in the of very light oils which circulatebetween the final compressor and the evaporation chamber, while the gas goes to exit from the final compressor system containing only very light oils, those which would be discarded in weathering gasoline recovered from the gas.

While the composition of natural gas is highly complex and the relations between thev vapor tensions and partial pressures of components* thereof correspondingly compli cated, the principles of the present invention may be understood by consideration of the properties of propane. Normal propane which boils, at atmospheric pressure, around 49 F., is always a component of these gases and it is one of the bodies removed in weathering casinghead gasoline. At 60 F., the pure gas is liquefied at a pressure of about 105 pounds. Assuming a gas containing 20 per cent propane, which is not an unusual amount, the gas would of course require 5 105, or 525 pounds pressure a (50 F. to

liquefythe propane. Presuming such a gas containing vapors of heavier oils. than propane, is put through the present process with the final temperature 60 F. and the pres- 's'ure somewhat below 525 pounds, some, but not all, of the propane will liquefy at this temperature and pressure and will join whatever other condensate may be formed. Now,

this .condensate be atomized in the passing gas 1n .the first stage of operation, the pro- .vpane will evaporate, producing an intense degree of refrigeration locally. Gasolinewill condense out of the gas but this gasoline will notcontain` much propane. So `far as propane is concerned, the gasoline will be as if it had-been weathered. Some ofthe propane which is evaporated into the gas will be again llquefied on submitting the gas to the final temperature of 60 F. at whatever pressure may be used. It Will then be conduct/ed back to the evaporation or spray chamber. So to speak, the pro ane will circulate in cyclic manner; a de nite amount of propane is evaporated in the chilling stage 4-and recondensed in the compression and cooling and so recirculating. While the eiluent gas will carry about the same amount of propane as the entering gas, thereis a local accumulation of propane which is vserving as a chilling agent. y

The actual relations are more complex and propane is merely cited in` explanation of the principle. f In actual operation, a quantity of the"very'lightest oils whichare not f desired in commercial gasoline but are exltremely good refrigerants, is retained in the system for circulation in the manner des cri'bed. So far as the gas is concerned, however, the net result is the same as if the light loils were not condensed, the amount in the eiuent gas being about the same as in the present system I employ lhigh chilling .and low pressure in the first stage, and little chilling but high pressure in the second stage; producing the high chilling in the first stage with the aid of condensatefrom the second stage. In producing the chilling effect, the frigorific agent, the lightest oils, is evaporated in actual contact with the gas to be chilled, thereby securing an efficient heat transfer. The unevaporated portion of the oils is an efficient scrubbing agent. In a measure, I am combining scrubbing, chilling and compression; but for the scrubbing and the chilling I use nothing foreign to the gas and I reserve high pressure fora second stage. The first stage operation may be at atmospheric pressure but is usually under line pressure. y

In the accompanying illustration I have shown, more or less diagrammatically, certain embodiments of my invention. In this showing,

Fig. 1 is a flow sheet diagram indicating one method of carrying out the process, while Fig 2 represents a modified method. Referring first to Fig. l, A represents a compressor of any ordinary or suitable type connected on the suction side of line 1 to a suitable source of natural or casinghead gas. B represents water-cooling means of ordinary construction. C is an accumulator tank for liquefied constituents coming from the compressed and cooled gas. Dindicates a precooler or heat exchanger, comprising an internal tube through which the gas passes in counter relationship to cooler gases passing through an external shell surrounding the internal tube. Eis a spray chamber, which is a suitable tank or chamber into which thegases to be cooled are conducted into contact with a spray .of liquid from line 9. F is an accumulator tank in which collects yunvolatilized liquid from the spray and condensed liquid from the gas. Vapors and gases from F are at a low temperature and pass through 45 into the xshell of the pre-cooler D, leaving thence through line 6 going to another compressor G. I-I is a Water cooling means and I is another accumulator tank for separating the gaseous and liquid constituents entering it.

Natural 'or casinghead gas from any source, if itrbe not already under whatever pressure may be desired, is vcompressed in the lcompressor A, passed through pipe 1 into the Water cooling means B wherein the heat of compression is extracted and is thence conducted into the accumulator tank C Where any liquid which has condensed is trapped olf through 10. The gas is then passed through line 2 into the pre-cooler D where it is brought into heat exchanging relation with cold gas coming from pipe 5. Passing from the heat exchanger, the cooled gas enters the spray chamber E by means ducted t of line 3. In the spray chamber, the gas is brought into intimate contact with liquid coming from line' 9 and undergoing selfevaporation. The chilled gases passent of the spray chamber throu h 4 and enter the second accumulator tank wherein the condensed and evaporated portions or relatively heavy oil constituents are trappedoff through 11. Uncondensed cold gas is taken oif the top of the tank F and conducted back to the pre-cooler through 5 and acts to cool incoming gas as previously described. Leaving the pre-cooler, the gas and vapors pass into the line 6 froin which all, or a part thereof,is passed to the compressor G. Only a part of the ases may be necessary for the purposes o? refri eration subsequently to be described, in w ich case the unneeded gas is Withdrawn from line 6 as shown.

The gas to be compressed for the purposes of 'refrigeration is compressed in G, con- H wherein t e heat of compression is extracted and passed to the accumulator tank I in which a part of the condensed liquid may be trappe oil' through 12. The uncondensed gas 1s conducted out of the system by line 8 and the 1i uid necessary for refrigeration is passed t rough line 9 back to the s ray chamber into which it is sprayed.

nly enough of the condensed liquid is passed into the spray chamber to cool the incoming. rich gases to that temperature at which the desired constituents will liquefy.

The refrigerating liquid, on being sprayed into the chamber E, evaporates in part thereby cooling the passing gas. Since thepressure in D, E and line 6 is kept substantially constant, evaporation of the liquid is continuous and the partial pressure of the lower boiling fractions cannot build up to the point where further evaporation is impossible.

In the modification shown -in Fig. 2, the

. apparatus elements are the same as in Fig. V1,

but with an additional heat exchanger K.

In the operation of the apparatus described in Fig. 1, gas conducted from the top of the accumulatr tank F by line 5 to ,the precooler D, is, in the modification shown in Fig. 2,' partly bypassed through line 13, through the heat exchanger K and by line f 14 back toline 6. This cold gas in passing through the heat exchanger K acts to further cool\the gases and condensed vapors leaving water cooler H and entering the accumulator I. By bypassing o a part of the gas leaving ythe accumulator tank F and through the heat exchanger K, further use is made of the cold gas as a cooling agent.

Asa further modification, a part of the compressed gas leaving the to Aof tank C maybe directly conducted, by line 15, to the suction side of the compressor G, if it is desired to do so.

rou h line 7 to water cooling means The temperature in the pre-cooler D may be thermostaticall controlled by a valve (not shown) regu ating the amount of gas entering D through 5, the rest of the gas being bypassed through 13.

What I claim is '1. In the direct production of marketable gasoline from natural gas, casinghead gas land the like, the process which comprises refrigerating pre-cooled gas under line pressure by evaporation of light oils thereinto, thereby condensing heavier oils, collecting and removing the condensed heavy oils, passing the residual gas from the refrigeration stage into heat exchanging relationship to the incomin gas toeiect pre-cooling thereof, thereafter ividing the gas so used into two portions, passing one portion to residue, compressing and cooling the remainin portion to condense light oils therefrom, and returning said condensed light oils to serve in refrigerating the incoming gas.

2. In the production of marketable gasoline from natural gas, casinghead gas and the like, the process which comprises refrigerating precooled gas under line pressure by the evaporation of light oils thereinto, thereby condensing heavier oils, collecting and removin the condensed heavy oils, passing a part o the refrigerated exit gas into heat exchanging` relationship to the incoming gas, then placing at least part of the exit gas under suilicient pressure to condense the light oils therefrom, cooling the compressed gas and passing it into heat exchanging relationship to another part of said refrigerated' exit gas and returning the condensed light oils to serve in refrigerating the precooled gas.

3. In an apparatus for the direct recovery of marketable gasoline from natural gas, casinghead gas and the like, a precooler, a spray chamber, means for conducting gas to be cooled into said precooler, means for conducting the cooled gas from said precooler to said (spray chamber, means for spraying a conensate of light oils into said spray chamber, means for separating the condensed heavy oils from the cold gas produced in the spray chamber and for conducting the' said separated cold gas to said pre-cooler, means for compressing at leastpart of said gas which has served as a cooling agentin said precooler chamber, means for spraying a condensate of light oils into the spray chamber, means for separating the condensed heavy oils from the cold gas produced in the spray chamber and for conducting the said separated cold gasto said pre-cooler, means for compressing and cooling the gas which has served. as a cooling a yent in the precooler to condense light oils t erefrom, means for passing gas from said spray chamber in heat exchanging relationship to the 'compressed gas to chill the same and means for conducting the said condensate of light oils to the said spraying means. n 1

In testimony whereof, I have hereunto affixed my signature.

. FRED E. HOSMER. 

